Synthesis transfer and characterization of core-shell gold-coated magnetic nanoparticles

摘要

class="kwd-title">Abbreviations: Fe3O4-AuNPs, core-shell gold-coated magnetic nanoparticles; HR-TEM, high-resolution transmission electron microscopy; (HR-TEM/EDS), high-resolution transmission electron microscopy with energy-dispersive X-ray spectroscopy; TMAOH, tetramethylammonium hydroxide; DMAP, 4-dimethyl(amino)pyridine class="kwd-title">Method name: Solvothermal synthesis of iron oxide nanoparticles with direct gold coating to form core-shell gold-coated magnetic nanoparticles, Phase transfer of core-shell gold-coated magnetic nanoparticles from organic to aqueous using 4-(dimethyl)amino pyridine (DMAP) as a phase transfer agent class="kwd-title">Keywords: Iron oxide, Gold-coated, Core-shell, Core-shell gold-coated magnetic nanoparticles, Magnetic separation, Fe3O4-AuNPs, 4-Dimethyl(amino)pyridine, DMAP, Nanoparticle phase transfer, Aqueous phase transfer, Solvothermal, Thin gold coating, Nanoparticle, Synthesis class="head no_bottom_margin" id="abs0010title">AbstractMagnetic separation has gained new popularity as a versatile partitioning method with the recent growth in nanotechnology and related biotechnology applications. In this study, iron oxide magnetic nanoparticles were synthesized via solvothermal methods and directly coated with gold to form core-shell gold-coated magnetic nanoparticles (Fe3O4-AuNPs). High-resolution transmission electron microscopy with Energy dispersive X-ray spectroscopy results suggests that temperature and reaction time play an important role in the formation of small, monodisperse Fe3O4-AuNPs. We also demonstrate that increased 4- dimethyl(amino)pyridine (DMAP) concentrations and vigorous stirring were required to successfully transfer Fe3O4-AuNPs into aqueous solution. The structure and morphology of the synthesized and transferred Fe3O4-AuNPs was further confirmed by UV–vis absorption spectroscopy and solubility experiments. class="first-line-outdent" id="lis0005">

• Direct coating of Fe3O4 with Au: Slowly heating by (10 °C/ min) until 180–190 °C without exceeding this reaction temperature and increasing the reaction time to 3 h from 1.5 h

• High yield transfer of Fe3O4-AuNPs was achieved using 4- dimethyl(amino)pyridine (DMAP) as phase transfer catalyst